#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;
#if NETSTANDARD1_3
using System.Runtime.InteropServices;
#else
using System.Configuration;
#endif
using System.Reflection;

using log4net.Util;
using log4net.Repository;

namespace log4net.Core
{
    /// <summary>
    /// Static manager that controls the creation of repositories
    /// </summary>
    /// <remarks>
    /// <para>
    /// Static manager that controls the creation of repositories
    /// </para>
    /// <para>
    /// This class is used by the wrapper managers (e.g. <see cref="log4net.LogManager"/>)
    /// to provide access to the <see cref="ILogger"/> objects.
    /// </para>
    /// <para>
    /// This manager also holds the <see cref="IRepositorySelector"/> that is used to
    /// lookup and create repositories. The selector can be set either programmatically using
    /// the <see cref="RepositorySelector"/> property, or by setting the <c>log4net.RepositorySelector</c>
    /// AppSetting in the applications config file to the fully qualified type name of the
    /// selector to use. 
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    /// <author>Gert Driesen</author>
    public sealed class LoggerManager
    {
        #region Private Instance Constructors

        /// <summary>
        /// Private constructor to prevent instances. Only static methods should be used.
        /// </summary>
        /// <remarks>
        /// <para>
        /// Private constructor to prevent instances. Only static methods should be used.
        /// </para>
        /// </remarks>
        private LoggerManager()
        {
        }

        #endregion Private Instance Constructors

        #region Static Constructor

        /// <summary>
        /// Hook the shutdown event
        /// </summary>
        /// <remarks>
        /// <para>
        /// On the full .NET runtime, the static constructor hooks up the 
        /// <c>AppDomain.ProcessExit</c> and <c>AppDomain.DomainUnload</c>> events. 
        /// These are used to shutdown the log4net system as the application exits.
        /// </para>
        /// </remarks>
        static LoggerManager()
        {
            try {
                // Register the AppDomain events, note we have to do this with a
                // method call rather than directly here because the AppDomain
                // makes a LinkDemand which throws the exception during the JIT phase.
                RegisterAppDomainEvents();
            }
            catch (System.Security.SecurityException) {
                LogLog.Debug(declaringType, "Security Exception (ControlAppDomain LinkDemand) while trying " +
                    "to register Shutdown handler with the AppDomain. LoggerManager.Shutdown() " +
                    "will not be called automatically when the AppDomain exits. It must be called " +
                    "programmatically.");
            }

            // Dump out our assembly version into the log if debug is enabled
            LogLog.Debug(declaringType, GetVersionInfo());

            // Set the default repository selector
#if NETCF
			s_repositorySelector = new CompactRepositorySelector(typeof(log4net.Repository.Hierarchy.Hierarchy));
			return;
#elif !NETSTANDARD1_3
            // Look for the RepositorySelector type specified in the AppSettings 'log4net.RepositorySelector'
            string appRepositorySelectorTypeName = SystemInfo.GetAppSetting("log4net.RepositorySelector");
            if (appRepositorySelectorTypeName != null && appRepositorySelectorTypeName.Length > 0) {
                // Resolve the config string into a Type
                Type appRepositorySelectorType = null;
                try {
                    appRepositorySelectorType = SystemInfo.GetTypeFromString(appRepositorySelectorTypeName, false, true);
                }
                catch (Exception ex) {
                    LogLog.Error(declaringType, "Exception while resolving RepositorySelector Type [" + appRepositorySelectorTypeName + "]", ex);
                }

                if (appRepositorySelectorType != null) {
                    // Create an instance of the RepositorySelectorType
                    object appRepositorySelectorObj = null;
                    try {
                        appRepositorySelectorObj = Activator.CreateInstance(appRepositorySelectorType);
                    }
                    catch (Exception ex) {
                        LogLog.Error(declaringType, "Exception while creating RepositorySelector [" + appRepositorySelectorType.FullName + "]", ex);
                    }

                    if (appRepositorySelectorObj != null && appRepositorySelectorObj is IRepositorySelector) {
                        s_repositorySelector = (IRepositorySelector)appRepositorySelectorObj;
                    }
                    else {
                        LogLog.Error(declaringType, "RepositorySelector Type [" + appRepositorySelectorType.FullName + "] is not an IRepositorySelector");
                    }
                }
            }
#endif
            // Create the DefaultRepositorySelector if not configured above 
            if (s_repositorySelector == null) {
                s_repositorySelector = new DefaultRepositorySelector(typeof(log4net.Repository.Hierarchy.Hierarchy));
            }
        }

        /// <summary>
        /// Register for ProcessExit and DomainUnload events on the AppDomain
        /// </summary>
        /// <remarks>
        /// <para>
        /// This needs to be in a separate method because the events make
        /// a LinkDemand for the ControlAppDomain SecurityPermission. Because
        /// this is a LinkDemand it is demanded at JIT time. Therefore we cannot
        /// catch the exception in the method itself, we have to catch it in the
        /// caller.
        /// </para>
        /// </remarks>
        private static void RegisterAppDomainEvents()
        {
#if !(NETCF || NETSTANDARD1_3)
            // ProcessExit seems to be fired if we are part of the default domain
            AppDomain.CurrentDomain.ProcessExit += new EventHandler(OnProcessExit);

            // Otherwise DomainUnload is fired
            AppDomain.CurrentDomain.DomainUnload += new EventHandler(OnDomainUnload);
#endif
        }

        #endregion Static Constructor

        #region Public Static Methods

        /// <summary>
        /// Return the default <see cref="ILoggerRepository"/> instance.
        /// </summary>
        /// <param name="repository">the repository to lookup in</param>
        /// <returns>Return the default <see cref="ILoggerRepository"/> instance</returns>
        /// <remarks>
        /// <para>
        /// Gets the <see cref="ILoggerRepository"/> for the repository specified
        /// by the <paramref name="repository"/> argument.
        /// </para>
        /// </remarks>
        [Obsolete("Use GetRepository instead of GetLoggerRepository")]
        public static ILoggerRepository GetLoggerRepository(string repository)
        {
            return GetRepository(repository);
        }

        /// <summary>
        /// Returns the default <see cref="ILoggerRepository"/> instance.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
        /// <returns>The default <see cref="ILoggerRepository"/> instance.</returns>
        [Obsolete("Use GetRepository instead of GetLoggerRepository")]
        public static ILoggerRepository GetLoggerRepository(Assembly repositoryAssembly)
        {
            return GetRepository(repositoryAssembly);
        }

        /// <summary>
        /// Return the default <see cref="ILoggerRepository"/> instance.
        /// </summary>
        /// <param name="repository">the repository to lookup in</param>
        /// <returns>Return the default <see cref="ILoggerRepository"/> instance</returns>
        /// <remarks>
        /// <para>
        /// Gets the <see cref="ILoggerRepository"/> for the repository specified
        /// by the <paramref name="repository"/> argument.
        /// </para>
        /// </remarks>
        public static ILoggerRepository GetRepository(string repository)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            return RepositorySelector.GetRepository(repository);
        }

        /// <summary>
        /// Returns the default <see cref="ILoggerRepository"/> instance.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
        /// <returns>The default <see cref="ILoggerRepository"/> instance.</returns>
        /// <remarks>
        /// <para>
        /// Returns the default <see cref="ILoggerRepository"/> instance.
        /// </para>
        /// </remarks>
        public static ILoggerRepository GetRepository(Assembly repositoryAssembly)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            return RepositorySelector.GetRepository(repositoryAssembly);
        }

        /// <summary>
        /// Returns the named logger if it exists.
        /// </summary>
        /// <param name="repository">The repository to lookup in.</param>
        /// <param name="name">The fully qualified logger name to look for.</param>
        /// <returns>
        /// The logger found, or <c>null</c> if the named logger does not exist in the
        /// specified repository.
        /// </returns>
        /// <remarks>
        /// <para>
        /// If the named logger exists (in the specified repository) then it
        /// returns a reference to the logger, otherwise it returns
        /// <c>null</c>.
        /// </para>
        /// </remarks>
        public static ILogger Exists(string repository, string name)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            if (name == null) {
                throw new ArgumentNullException("name");
            }
            return RepositorySelector.GetRepository(repository).Exists(name);
        }

        /// <summary>
        /// Returns the named logger if it exists.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
        /// <param name="name">The fully qualified logger name to look for.</param>
        /// <returns>
        /// The logger found, or <c>null</c> if the named logger does not exist in the
        /// specified assembly's repository.
        /// </returns>
        /// <remarks>
        /// <para>
        /// If the named logger exists (in the specified assembly's repository) then it
        /// returns a reference to the logger, otherwise it returns
        /// <c>null</c>.
        /// </para>
        /// </remarks>
        public static ILogger Exists(Assembly repositoryAssembly, string name)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            if (name == null) {
                throw new ArgumentNullException("name");
            }
            return RepositorySelector.GetRepository(repositoryAssembly).Exists(name);
        }

        /// <summary>
        /// Returns all the currently defined loggers in the specified repository.
        /// </summary>
        /// <param name="repository">The repository to lookup in.</param>
        /// <returns>All the defined loggers.</returns>
        /// <remarks>
        /// <para>
        /// The root logger is <b>not</b> included in the returned array.
        /// </para>
        /// </remarks>
        public static ILogger[] GetCurrentLoggers(string repository)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            return RepositorySelector.GetRepository(repository).GetCurrentLoggers();
        }

        /// <summary>
        /// Returns all the currently defined loggers in the specified assembly's repository.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
        /// <returns>All the defined loggers.</returns>
        /// <remarks>
        /// <para>
        /// The root logger is <b>not</b> included in the returned array.
        /// </para>
        /// </remarks>
        public static ILogger[] GetCurrentLoggers(Assembly repositoryAssembly)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            return RepositorySelector.GetRepository(repositoryAssembly).GetCurrentLoggers();
        }

        /// <summary>
        /// Retrieves or creates a named logger.
        /// </summary>
        /// <param name="repository">The repository to lookup in.</param>
        /// <param name="name">The name of the logger to retrieve.</param>
        /// <returns>The logger with the name specified.</returns>
        /// <remarks>
        /// <para>
        /// Retrieves a logger named as the <paramref name="name"/>
        /// parameter. If the named logger already exists, then the
        /// existing instance will be returned. Otherwise, a new instance is
        /// created.
        /// </para>
        /// <para>
        /// By default, loggers do not have a set level but inherit
        /// it from the hierarchy. This is one of the central features of
        /// log4net.
        /// </para>
        /// </remarks>
        public static ILogger GetLogger(string repository, string name)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            if (name == null) {
                throw new ArgumentNullException("name");
            }
            return RepositorySelector.GetRepository(repository).GetLogger(name);
        }

        /// <summary>
        /// Retrieves or creates a named logger.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
        /// <param name="name">The name of the logger to retrieve.</param>
        /// <returns>The logger with the name specified.</returns>
        /// <remarks>
        /// <para>
        /// Retrieves a logger named as the <paramref name="name"/>
        /// parameter. If the named logger already exists, then the
        /// existing instance will be returned. Otherwise, a new instance is
        /// created.
        /// </para>
        /// <para>
        /// By default, loggers do not have a set level but inherit
        /// it from the hierarchy. This is one of the central features of
        /// log4net.
        /// </para>
        /// </remarks>
        public static ILogger GetLogger(Assembly repositoryAssembly, string name)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            if (name == null) {
                throw new ArgumentNullException("name");
            }
            return RepositorySelector.GetRepository(repositoryAssembly).GetLogger(name);
        }

        /// <summary>
        /// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
        /// </summary>
        /// <param name="repository">The repository to lookup in.</param>
        /// <param name="type">The <paramref name="type"/> of which the fullname will be used as the name of the logger to retrieve.</param>
        /// <returns>The logger with the name specified.</returns>
        /// <remarks>
        /// <para>
        /// Gets the logger for the fully qualified name of the type specified.
        /// </para>
        /// </remarks>
        public static ILogger GetLogger(string repository, Type type)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            if (type == null) {
                throw new ArgumentNullException("type");
            }
            return RepositorySelector.GetRepository(repository).GetLogger(type.FullName);
        }

        /// <summary>
        /// Shorthand for <see cref="M:LogManager.GetLogger(string)"/>.
        /// </summary>
        /// <param name="repositoryAssembly">the assembly to use to lookup the repository</param>
        /// <param name="type">The <paramref name="type"/> of which the fullname will be used as the name of the logger to retrieve.</param>
        /// <returns>The logger with the name specified.</returns>
        /// <remarks>
        /// <para>
        /// Gets the logger for the fully qualified name of the type specified.
        /// </para>
        /// </remarks>
        public static ILogger GetLogger(Assembly repositoryAssembly, Type type)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            if (type == null) {
                throw new ArgumentNullException("type");
            }
            return RepositorySelector.GetRepository(repositoryAssembly).GetLogger(type.FullName);
        }

        /// <summary>
        /// Shuts down the log4net system.
        /// </summary>
        /// <remarks>
        /// <para>
        /// Calling this method will <b>safely</b> close and remove all
        /// appenders in all the loggers including root contained in all the
        /// default repositories.
        /// </para>
        /// <para>
        /// Some appenders need to be closed before the application exists. 
        /// Otherwise, pending logging events might be lost.
        /// </para>
        /// <para>
        /// The <c>shutdown</c> method is careful to close nested
        /// appenders before closing regular appenders. This is allows
        /// configurations where a regular appender is attached to a logger
        /// and again to a nested appender.
        /// </para>
        /// </remarks>
        public static void Shutdown()
        {
            foreach (ILoggerRepository repository in GetAllRepositories()) {
                repository.Shutdown();
            }
        }

        /// <summary>
        /// Shuts down the repository for the repository specified.
        /// </summary>
        /// <param name="repository">The repository to shutdown.</param>
        /// <remarks>
        /// <para>
        /// Calling this method will <b>safely</b> close and remove all
        /// appenders in all the loggers including root contained in the
        /// repository for the <paramref name="repository"/> specified.
        /// </para>
        /// <para>
        /// Some appenders need to be closed before the application exists. 
        /// Otherwise, pending logging events might be lost.
        /// </para>
        /// <para>
        /// The <c>shutdown</c> method is careful to close nested
        /// appenders before closing regular appenders. This is allows
        /// configurations where a regular appender is attached to a logger
        /// and again to a nested appender.
        /// </para>
        /// </remarks>
        public static void ShutdownRepository(string repository)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            RepositorySelector.GetRepository(repository).Shutdown();
        }

        /// <summary>
        /// Shuts down the repository for the repository specified.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository.</param>
        /// <remarks>
        /// <para>
        /// Calling this method will <b>safely</b> close and remove all
        /// appenders in all the loggers including root contained in the
        /// repository for the repository. The repository is looked up using
        /// the <paramref name="repositoryAssembly"/> specified.
        /// </para>
        /// <para>
        /// Some appenders need to be closed before the application exists. 
        /// Otherwise, pending logging events might be lost.
        /// </para>
        /// <para>
        /// The <c>shutdown</c> method is careful to close nested
        /// appenders before closing regular appenders. This is allows
        /// configurations where a regular appender is attached to a logger
        /// and again to a nested appender.
        /// </para>
        /// </remarks>
        public static void ShutdownRepository(Assembly repositoryAssembly)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            RepositorySelector.GetRepository(repositoryAssembly).Shutdown();
        }

        /// <summary>
        /// Resets all values contained in this repository instance to their defaults.
        /// </summary>
        /// <param name="repository">The repository to reset.</param>
        /// <remarks>
        /// <para>
        /// Resets all values contained in the repository instance to their
        /// defaults.  This removes all appenders from all loggers, sets
        /// the level of all non-root loggers to <c>null</c>,
        /// sets their additivity flag to <c>true</c> and sets the level
        /// of the root logger to <see cref="Level.Debug"/>. Moreover,
        /// message disabling is set its default "off" value.
        /// </para>		
        /// </remarks>
        public static void ResetConfiguration(string repository)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            RepositorySelector.GetRepository(repository).ResetConfiguration();
        }

        /// <summary>
        /// Resets all values contained in this repository instance to their defaults.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to lookup the repository to reset.</param>
        /// <remarks>
        /// <para>
        /// Resets all values contained in the repository instance to their
        /// defaults.  This removes all appenders from all loggers, sets
        /// the level of all non-root loggers to <c>null</c>,
        /// sets their additivity flag to <c>true</c> and sets the level
        /// of the root logger to <see cref="Level.Debug"/>. Moreover,
        /// message disabling is set its default "off" value.
        /// </para>		
        /// </remarks>
        public static void ResetConfiguration(Assembly repositoryAssembly)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            RepositorySelector.GetRepository(repositoryAssembly).ResetConfiguration();
        }

        /// <summary>
        /// Creates a repository with the specified name.
        /// </summary>
        /// <param name="repository">The name of the repository, this must be unique amongst repositories.</param>
        /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
        /// <remarks>
        /// <para>
        /// <b>CreateDomain is obsolete. Use CreateRepository instead of CreateDomain.</b>
        /// </para>
        /// <para>
        /// Creates the default type of <see cref="ILoggerRepository"/> which is a
        /// <see cref="log4net.Repository.Hierarchy.Hierarchy"/> object.
        /// </para>
        /// <para>
        /// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
        /// An <see cref="Exception"/> will be thrown if the repository already exists.
        /// </para>
        /// </remarks>
        /// <exception cref="LogException">The specified repository already exists.</exception>
        [Obsolete("Use CreateRepository instead of CreateDomain")]
        public static ILoggerRepository CreateDomain(string repository)
        {
            return CreateRepository(repository);
        }

        /// <summary>
        /// Creates a repository with the specified name.
        /// </summary>
        /// <param name="repository">The name of the repository, this must be unique amongst repositories.</param>
        /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
        /// <remarks>
        /// <para>
        /// Creates the default type of <see cref="ILoggerRepository"/> which is a
        /// <see cref="log4net.Repository.Hierarchy.Hierarchy"/> object.
        /// </para>
        /// <para>
        /// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
        /// An <see cref="Exception"/> will be thrown if the repository already exists.
        /// </para>
        /// </remarks>
        /// <exception cref="LogException">The specified repository already exists.</exception>
        public static ILoggerRepository CreateRepository(string repository)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            return RepositorySelector.CreateRepository(repository, null);
        }

        /// <summary>
        /// Creates a repository with the specified name and repository type.
        /// </summary>
        /// <param name="repository">The name of the repository, this must be unique to the repository.</param>
        /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
        /// and has a no arg constructor. An instance of this type will be created to act
        /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
        /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
        /// <remarks>
        /// <para>
        /// <b>CreateDomain is obsolete. Use CreateRepository instead of CreateDomain.</b>
        /// </para>
        /// <para>
        /// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
        /// An Exception will be thrown if the repository already exists.
        /// </para>
        /// </remarks>
        /// <exception cref="LogException">The specified repository already exists.</exception>
        [Obsolete("Use CreateRepository instead of CreateDomain")]
        public static ILoggerRepository CreateDomain(string repository, Type repositoryType)
        {
            return CreateRepository(repository, repositoryType);
        }

        /// <summary>
        /// Creates a repository with the specified name and repository type.
        /// </summary>
        /// <param name="repository">The name of the repository, this must be unique to the repository.</param>
        /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
        /// and has a no arg constructor. An instance of this type will be created to act
        /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
        /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
        /// <remarks>
        /// <para>
        /// The <paramref name="repository"/> name must be unique. Repositories cannot be redefined.
        /// An Exception will be thrown if the repository already exists.
        /// </para>
        /// </remarks>
        /// <exception cref="LogException">The specified repository already exists.</exception>
        public static ILoggerRepository CreateRepository(string repository, Type repositoryType)
        {
            if (repository == null) {
                throw new ArgumentNullException("repository");
            }
            if (repositoryType == null) {
                throw new ArgumentNullException("repositoryType");
            }
            return RepositorySelector.CreateRepository(repository, repositoryType);
        }

        /// <summary>
        /// Creates a repository for the specified assembly and repository type.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to get the name of the repository.</param>
        /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
        /// and has a no arg constructor. An instance of this type will be created to act
        /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
        /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
        /// <remarks>
        /// <para>
        /// <b>CreateDomain is obsolete. Use CreateRepository instead of CreateDomain.</b>
        /// </para>
        /// <para>
        /// The <see cref="ILoggerRepository"/> created will be associated with the repository
        /// specified such that a call to <see cref="M:GetRepository(Assembly)"/> with the
        /// same assembly specified will return the same repository instance.
        /// </para>
        /// </remarks>
        [Obsolete("Use CreateRepository instead of CreateDomain")]
        public static ILoggerRepository CreateDomain(Assembly repositoryAssembly, Type repositoryType)
        {
            return CreateRepository(repositoryAssembly, repositoryType);
        }

        /// <summary>
        /// Creates a repository for the specified assembly and repository type.
        /// </summary>
        /// <param name="repositoryAssembly">The assembly to use to get the name of the repository.</param>
        /// <param name="repositoryType">A <see cref="Type"/> that implements <see cref="ILoggerRepository"/>
        /// and has a no arg constructor. An instance of this type will be created to act
        /// as the <see cref="ILoggerRepository"/> for the repository specified.</param>
        /// <returns>The <see cref="ILoggerRepository"/> created for the repository.</returns>
        /// <remarks>
        /// <para>
        /// The <see cref="ILoggerRepository"/> created will be associated with the repository
        /// specified such that a call to <see cref="M:GetRepository(Assembly)"/> with the
        /// same assembly specified will return the same repository instance.
        /// </para>
        /// </remarks>
        public static ILoggerRepository CreateRepository(Assembly repositoryAssembly, Type repositoryType)
        {
            if (repositoryAssembly == null) {
                throw new ArgumentNullException("repositoryAssembly");
            }
            if (repositoryType == null) {
                throw new ArgumentNullException("repositoryType");
            }
            return RepositorySelector.CreateRepository(repositoryAssembly, repositoryType);
        }

        /// <summary>
        /// Gets an array of all currently defined repositories.
        /// </summary>
        /// <returns>An array of all the known <see cref="ILoggerRepository"/> objects.</returns>
        /// <remarks>
        /// <para>
        /// Gets an array of all currently defined repositories.
        /// </para>
        /// </remarks>
        public static ILoggerRepository[] GetAllRepositories()
        {
            return RepositorySelector.GetAllRepositories();
        }

        /// <summary>
        /// Gets or sets the repository selector used by the <see cref="LogManager" />.
        /// </summary>
        /// <value>
        /// The repository selector used by the <see cref="LogManager" />.
        /// </value>
        /// <remarks>
        /// <para>
        /// The repository selector (<see cref="IRepositorySelector"/>) is used by 
        /// the <see cref="LogManager"/> to create and select repositories 
        /// (<see cref="ILoggerRepository"/>).
        /// </para>
        /// <para>
        /// The caller to <see cref="LogManager"/> supplies either a string name 
        /// or an assembly (if not supplied the assembly is inferred using 
        /// <see cref="M:Assembly.GetCallingAssembly()"/>).
        /// </para>
        /// <para>
        /// This context is used by the selector to lookup a specific repository.
        /// </para>
        /// <para>
        /// For the full .NET Framework, the default repository is <c>DefaultRepositorySelector</c>;
        /// for the .NET Compact Framework <c>CompactRepositorySelector</c> is the default
        /// repository.
        /// </para>
        /// </remarks>
        public static IRepositorySelector RepositorySelector
        {
            get { return s_repositorySelector; }
            set { s_repositorySelector = value; }
        }

        #endregion Public Static Methods

        #region Private Static Methods

        /// <summary>
        /// Internal method to get pertinent version info.
        /// </summary>
        /// <returns>A string of version info.</returns>
        private static string GetVersionInfo()
        {
            System.Text.StringBuilder sb = new System.Text.StringBuilder();

#if NETSTANDARD1_3
			Assembly myAssembly = typeof(LoggerManager).GetTypeInfo().Assembly;
			sb.Append($"log4net assembly [{myAssembly.FullName}]. ");
			//sb.Append($"Loaded from [{myAssembly.Location}]. "); // TODO Assembly.Location available in netstandard1.5
			sb.Append($"(.NET Framework [{RuntimeInformation.FrameworkDescription}] on {RuntimeInformation.OSDescription}");
#else
            Assembly myAssembly = Assembly.GetExecutingAssembly();
            sb.Append("log4net assembly [").Append(myAssembly.FullName).Append("]. ");
            sb.Append("Loaded from [").Append(SystemInfo.AssemblyLocationInfo(myAssembly)).Append("]. ");
            sb.Append("(.NET Runtime [").Append(Environment.Version.ToString()).Append("]");
#if (!SSCLI)
            sb.Append(" on ").Append(Environment.OSVersion.ToString());
#endif
#endif // NETSTANDARD1_3
            sb.Append(")");
            return sb.ToString();
        }

#if (!NETCF)
        /// <summary>
        /// Called when the <see cref="AppDomain.DomainUnload"/> event fires
        /// </summary>
        /// <param name="sender">the <see cref="AppDomain"/> that is exiting</param>
        /// <param name="e">null</param>
        /// <remarks>
        /// <para>
        /// Called when the <see cref="AppDomain.DomainUnload"/> event fires.
        /// </para>
        /// <para>
        /// When the event is triggered the log4net system is <see cref="M:Shutdown()"/>.
        /// </para>
        /// </remarks>
        private static void OnDomainUnload(object sender, EventArgs e)
        {
            Shutdown();
        }

        /// <summary>
        /// Called when the <see cref="AppDomain.ProcessExit"/> event fires
        /// </summary>
        /// <param name="sender">the <see cref="AppDomain"/> that is exiting</param>
        /// <param name="e">null</param>
        /// <remarks>
        /// <para>
        /// Called when the <see cref="AppDomain.ProcessExit"/> event fires.
        /// </para>
        /// <para>
        /// When the event is triggered the log4net system is <see cref="M:Shutdown()"/>.
        /// </para>
        /// </remarks>
        private static void OnProcessExit(object sender, EventArgs e)
        {
            Shutdown();
        }
#endif

        #endregion Private Static Methods

        #region Private Static Fields

        /// <summary>
        /// The fully qualified type of the LoggerManager class.
        /// </summary>
        /// <remarks>
        /// Used by the internal logger to record the Type of the
        /// log message.
        /// </remarks>
        private readonly static Type declaringType = typeof(LoggerManager);

        /// <summary>
        /// Initialize the default repository selector
        /// </summary>
        private static IRepositorySelector s_repositorySelector;

        #endregion Private Static Fields
    }
}
